Kerf cutting device



7 July 14, 1942. L. E. SIMMONS 2,239,464

KERR-CUTTING DEVICE Filed Aug. 10, 1959 van/for.-

ZeonE. 721710726.

A ,4 JMMM Patented July 14, 1942 KERF CUTTING DEVICE Leon E. Simmons, Claremont, N. H., assignor to Sullivan Machinery Company,.a corporation of Massachusetts Application August 10, 193-9, Serial No. 289,450

4 Claims.

This invention relates to cutting devices-particularly to cutting devices utilized in coal cutting machines-and from one aspect it relates more particularly to cutter bits, and more'especially to improvements in cutter bits of the multi-pointed reversible type especially designed for use in a cutter chain of a coal cutting machine.

In cutter bits of the type employed in the cutter chains of a coal cutting machine, it is well known to provide two or more cutting points in a single bit, so that when one point becomes dull the bit can be rearranged on the chain block, thereby to present a sharp point to the work, and such multi-pointed reversible bits are usually cheap in initial cost so that they may be discarded when all points become dull. The main disadvantage of such multi-pointed, reversible cutter bits is that a special form of relatively complicated holder is generally necessary to hold the bits in cutting position ;on the blocks of the cutter chain, or else a special form of block is required. So far as it is known, no'satisfactory commercially successful cutter bit of the multipointed reversible type has been devised which can be supported in the standard cutter chain blocks of a cutter chain :without the use of special supports andholding devices.

A primary object of the present invention is to provide an improved cutting instrumen'tality. Another object is to provide a multi-pointed reversible cutter bit of 'an extremely inexpensive and efficient design which may be supported in the standard cutter blocksof .a cutter chain and held in position in the chain blocks by the usual bit holding set screws. vAnother object is to provide a cutter bit of the double-pointed reversible type of an improved shape and construction. Yet another object -is .to provide .a double-pointed reversible cutter bit of an improved design wherein the inactive cutting portion of the bit-serves as the shank of the active bit-cutting portion so that the conventional set screw of a standard cutter chain can engage the inactive or shankserving portion to hold the cutter bit in cutting position on the chain block. Other objects and advantages of the invention will, however, here-.

inafter more fully appear.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

In the drawing:

Fig. 1 is a fragmentary side elevational view of a cutter chain equipped with my improved may obtain access to the socket 4.

cutter-bit and together with the latter providing an improved cutter-chain-type cutting unit.

Fig. 2 is a cross sectional view taken substantially on lin 2--2 of Fig. 1, showing the chain block and cutter bit in end elevation.

Fig. 3 is a viewin longitudinal section taken substantially on line 33 of Fig. 2.

Fig. 4 is a cross sectional view takensubstantially on line '44of Fig. 1.

Fig. 5 is a perspective view of the improved cutter bit.

Fig. 6 is a detail sectional view taken on line 6-6 of Fig. 3.

Fig. 7 is a detail sectional view taken on line 1-1 of Fig. 3.

Fig. 8 is a cross sectional View taken on ,line 88 of Fig. 5.

In this illustrative construction, the improved cutter bit is shown associated with a standard cutter, chain comprising a series of. chain blocks I pivotally connected together by strap links 2. The chain blocks each have a projecting lug 3 provided with a bit-receiving aperture or socket 4, herein generally rectangular in cross section and extending at .right angles to the path of travel of the cutter chain. The chain block .is formed at the opposite ends of the bit-receiving socket with threaded openings 5, 5 for selectivelyreceiving a conventional, .or standard, set screw 5. Traversing the blockis a bore 1 whereby the breaching of the socket. 4,.is facilitated during manufacture, and access to the inner inactive cutting end of the cutter bit is obtained. This opening also enables the escape ofv cuttings which The block socket 4 is adapted 'toreceive a cutter bit, generally designated 8,, ofan improved design.

As illustrated, the improved cutter bit 3 is of the double-ended reversible type having a central body portion 9 of rectangular cross section, and is preferably made of .a drop forging, although if desired it may be made of flatbar stock formed as by bending and rolling into shape. Instead of employing a fiat rectangular T cross section, it is evident that the bit body may be formed of various other shapes without departing from, the spirit of .the invention. 'Projecting symmetrically from the bit body are cutting portions l0, l0 forming the cutting points ll, 1 I, these cutting portions being mutually inclined and having their front cuttingfaces l2 extending from the cutting points angularly with respect'to each other and lying in. planes extending approximately to the longitudinal center of the bit. The shape of the cutting portions may be varied, depending upon the requirements of the work, but, in this instance, these are preferably generally semi-elliptical in shape, as shown in Fig. 6. The cutting portions II], II] have at their sides opposite from the cutting faces, plane rear surfaces l3, [3 preferably arranged in parallelism with the cutting faces, and the planes including the cutting faces and the planes including these rear surfaces respectively intersect at the front and the back of the bit at the center of the latter, midway between the extremities of the cutting points. Each cutting portion of the bit is substantially the same in shape as that of a standard single-pointed shanked bit which is in common use. The dihedral angle formed by the planes of the cutting faces is such that the active point is presented at the proper argle when the bit is positioned on the block, and the inner portion of the active cutting face engages the outer surface of the block at [4 so as to obtain accurate gauging of the bit without the use of special gauging devices. There is, however, possible a limited amount of adjustment of the bit within the block socket so that the gauge of the bit may be varied, this being desirable in case of resharpening or wearing down of the bit points. The rectangular central body portion of the bit, as shown in Fig. '7, fits snugly the Walls of the rectangular block socket laterally, and the set screw 6, engaging the inactive cutting face of the bit, holds the bit firmly against the rear socket wall. When the cutter bit is properly positioned in the chain block socket, as shown in Fig. 3, the inactive cutting portion of the bit extends within the block socket while the active cutting portion is forwardly and outwardly inclined. The rear surface l3 of the inactive cutting portion abuttingly engages the rear wall of the block socket 4, and the set screw 6, when tightened, engages the inactive cutting face l2 of the bit to clamp the rear bit surface firmly against the rear socket wall. If it is desired to reverse the direction of travel of the cutter chain, this may be accomplished simply by reversing the position of the bits on the chain blocks and transposing the set screws to the other threaded openings 5 in the blocks.

It is accordingly evident that an improved cutter bit of the double-ended reversible type is provided which may be associated with a cutter block of a standard cutter chain and held in position on the block without the use of special positioning and holding devices. The block and bit construction, as above described, affords a simple and durable construction in which the cutter bit has double cutting ends and these cuttings ends are inclined forwardly of the main body of the bit and may be securely clamped in place at the proper angle on the chain block. The cutter bit is maintained in engagement with an abutment surface along its rear face which is particularly desirable in cutter chains of this character, and said bit projects from the cutter block at a forwardly inclined angle, thereby increasing the cutting efficiency of the bit. Other uses and advantages of the improved cutter bit will be clearly apparent to those skilled in the art.

It will be apparent that the bit may be considered as made up of a pair of straight portions joined by a wedge portion pointed forwardly. And in the construction shown for illustration the angle between the opposite cutting ends of the bit is equal to the sum of the angle of the bit socket to its bit path and the angle of the working face of the bit to that path.

While there is in this-application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a cutter bit, a body terminating at its opposite ends in cutting points at the same side of the bit and having its halves at the opposite ends thereof alike and relatively inclined, and each half having parallel front and rear surfaces making like angles, less than right angles, with a plane bisecting the bit, and each half having an outer surface extending rearwardly from its respective cutting point and making an acute angle with its forward surface, the apex of which angle is at the cutting point.

2. A double-ended cutter bit comprising a body of symmetrical shape having relatively inclined cutting portions terminating in cutting points at their remote extremities at the same side of the bit body, said relatively inclined cutting portions each having a plane forward face and a parallel rear face of shorter length than said forward face, and an outer surface receding from the cutting point and extending between said forward and rear faces, the planes in which said forward faces lie and the planes in which said rear faces lie intersecting in lines lying in a plane bisecting the bit body midway between the cutting points.

3. In a cutter chain, the combination comprising a standard chain block having a socket extending perpendicular to the path of travel of the chain and of uniform cross section and a threaded opening entering said socket at the forward side of said block and adapted to receive a standard set screw, a double-ended cutter bit comprising a body of symmetrical shape having relatively inclined cutting portions terminating in cutting points at their remote extremities at the same side of the bit body, said relatively inclined cutting portions each having a plane forward face and a parallel rear face of shorter length than said forward face and an outer surface receding from the cutting point and extending between said forward and rear faces, the planes in which said forward faces lie and the planes in which said rear faces lie intersecting in lines lying in a plane bisecting the bit body midway between the cutting points, the inactive cutting portion of the bit being receivable in said block socket and the central portion of the bit body being of approximately the same cross section as and substantially fitting the block socket, the rear plane face of the inactive cutting portion engaging the rear socket wall and the active cutting portion projecting outwardly from and inclined forwardly relative to the block socket, and a standard set screw receivable within said threaded opening and engageable with the forward plane face of the inactive cutting portion for securing the cutter bit in cutting position in said block socket.

4. In a cutter chain, the combination comprising a standard chain block having a socket extending perpendicular to the path of travel of the chain and of uniform cross section and a thread-' ed opening entering said socket at the forward side of said block and adapted to receive a standard set screw, a double-ended cutter bit comprising a body of symmetrical shape having relatively inclined cutting portions terminating in cutting points at their remote extremities at the same side of the bit body, said relatively inclined cutting portions each having a plane forward face and a parallel rear face of shorter length than said forward face and an outer surface receding from the cutting point and extending between said forward and rear faces, the planes in which said forwardfaces lie and the planes in which said rear faces lie intersecting in lines lying in a plane bisecting the bit body midway between the cutting points, the inactive cutting portion of the bit being receivable in said block socket and the central portion of the bit body being ofapproximately the same cross section as and substantially fitting the .block socket, the rear plane face of the inactive cutting portion engaging the rear socket wall and the active cutting portion projecting outwardly from and inclined forwardly relative to the block socket with its forward face engaging the outer edge of the front socket wall, and a standard set screw receivable within said threaded opening and engageable with the forward plane face of the inactive cutting portion for securing the cutter bit in cutting position in said block socket.

LEON E. SIMMONS. 

